Heavy metal distribution in sediments of Muthupettai mangroves, south east coast of India     

B.Thilagavathi  K.Raja  Bandana Das  A.Saravanakumar  S.Vijayalakshmi  T.Balasubramanian 《中国海洋大学学报(英文版)》2011,10(4):385-390

Core sediments from the Muthupettai mangroves on the southeast coast of India were analyzed for soil texture,total nitrogen,organic carbon,phosphorus and heavy metals(Fe,Mn,Cr,Cu,Ni,Pb,Zn and Cd).The distinct seasonal variation in the distribution of metals in the sediments was observed.The minimum concentration was recorded in river mouth and the maximum was in lagoon.High metal concentration in sediment was observed during monsoon and low concentration in summer.The total nu-trient in lagoon and river mouth was recorded in the range of 4.528 to 8.526 mg g-1 for organic carbon,2.213 to 10.5 mg g-1 for nitro-gen and 0.824 to 7.22 mg g-1.  相似文献   

Characterizing spatial variability of soil properties in salt affected coastal India using geostatistics and kriging   总被引：2，自引：0，他引：2  

Rahul Tripathi  A. K. Nayak  Mohammad Shahid  R. Raja  B. B. Panda  S. Mohanty  Anjani Kumar  B. Lal  Priyanka Gautam  R. N. Sahoo 《Arabian Journal of Geosciences》2015,8(12):10693-10703

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Narrow-Band Imaging System for the Multi-application Solar Telescope at Udaipur Solar Observatory: Characterization of Lithium Niobate Etalons     

A. Raja Bayanna  Shibu K. Mathew  P. Venkatakrishnan  N. Srivastava 《Solar physics》2014,289(10):4007-4019

The Multi-application Solar Telescope is a 50 cm off-axis Gregorian telescope that has been installed at the lake site of Udaipur Solar Observatory. For quasi-simultaneous photospheric and chromospheric observations, a narrow-band imager has been developed as one of the back-end instruments for this telescope. Narrow-band imaging is achieved using two lithium niobate Fabry–Perot etalons working in tandem as a filter. This filter can be tuned to different wavelengths by changing either voltage, tilt, or temperature of the etalons. To characterize the etalons, a Littrow spectrograph was set up in conjunction with a 15 cm Carl Zeiss Coudé solar telescope. The etalons were calibrated for the solar spectral lines Fe i 6173 Å, and Ca ii 8542 Å. In this work, we discuss the characterization of the Fabry–Perot etalons, specifically, the temperature and voltage tuning of the system for the spectral lines proposed for observations. We present the details of the calibration set-up and various tuning parameters. We also present solar images obtained using the system.  相似文献   

Dynamics of Sunspot Light Bridges as Revealed by High-Resolution Images from <Emphasis Type="Italic">Hinode</Emphasis>     

Rohan E. Louis  A. Raja Bayanna  Shibu K. Mathew  P. Venkatakrishnan 《Solar physics》2008,252(1):43-54

We present G-band and Ca ii H filtergrams of two sunspot light bridges in NOAA AR 10953 taken from the 50-cm Solar Optical Telescope onboard the Japanese space satellite Hinode on 1 May 2007. The two light bridges differ in structure, with one of them resembling the filamentary penumbra and the other possessing a dark central lane running along the axis of the bridge having a width of 170 km, which is close to the diffraction limit of the telescope. Velocity measurements of the light bridges using proper motion displacements of inhomogeneities, averaged over the entire time series, show a nonuniform flow with velocities peaking at 250 and 180 m s⁻¹ for the two bridges, respectively. We report observations of an archlike structure over one of the light bridges in the Ca images. Brightness enhancements are seen traveling along this arch as well as along the light bridge. Observations suggest that these enhancements over light bridges could possibly be a signature of lower chromospheric heating.  相似文献   

Spatial Scale Effects of Climate Scenarios on Simulated Cotton Production in the Southeastern U.S.A.     

Ruth M. Doherty  Linda O. Mearns  K. Raja Reddy  Mary W. Downton  Larry McDaniel 《Climatic change》2003,60(1-2):99-129

We examine the effect of climate scenarios generated using results from climate models of different spatial resolution on yields simulated by the deterministic cotton model GOSSYM for the southeastern U.S.A. Two related climate change scenarios were used: a coarse-scale scenario produced from results of a general circulation model (GCM) which also provided the boundary conditions to a regional climate model (RCM), from which a fine-scale scenario was constructed. Cotton model simulations were performed for three cases: climate change alone; climate change and elevatedCO₂; climate change, elevated CO₂ and adaptations to climate change. In general, significant differences in state-average projected yield changes between the coarse and fine-scale scenarios are found for these three cases. In the first two cases, different directions of change are found in some sub-regions. With adaptation, yields substantially increase for both climate scenarios, but more so for the coarse-scale scenario (30%domain-average increase). Under irrigation, yield change differences between the two climate scenarios are small in all three cases, and yields are higher under irrigation ( 35% domain-average increase with adaptation case) compared to dryland conditions. For the climate change alone case, differences in summer water-stress levels explain the contrasts in dryland yield patterns between the coarse and fine-scale climate scenarios.  相似文献   

Characterization of organic matter deposited in the oriental zone from Moknine hypersaline environment, oriental Tunisia     

Raja CHAIRI Zohra EL ASMI DJELLOULI 《中国地球化学学报》2005,24(4):345-351

The geochemistry data show that the total organic carbon （TOC） contents are high in the surface sediments in the eastern part of the Moknine＇ s Sebkha. Low decreasing of organic matter （ OM ） with increasing depth indicates the good preservation of OM in modern sediments. ＂Lignite levels＂ inserted in the sand sequence and deposited at the edge and in the intermediate zone are considered as lithologic and organic markers. It is characterized by high TOC and poor hydrogen index （HI） , indicating a higher plant origin and good preservation of OM in thin beds under anoxic condition. In all samples low values of HI are typical for strong terrigenous input in the Sebkha. Gas chromatography （GC） of saturate fraction showed that OM in the border zone is provided from plants but in the central zone OM is a mixture of terrestrial fraction and little fraction from microalgae. The study of free lipids indicated that this environment was influenced by intense bacterial and microbial activities, as evidenced by the abundance of n-alkanes and nC18-nC22.  相似文献   

The Palaeomagnetism of the Kisii Series, Western Kenya     

A. Brock  P. K. S. Raja  J. B. Vise 《Geophysical Journal International》1972,28(2):129-137

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Paleomagnetic results from the Narosura and Magadi volcanics of Kenya     

J.P. Patel  P.K.S. Raja 《Physics of the Earth and Planetary Interiors》1979,19(3):P7-P14

Results of a paleomagnetic study carried out on the exposed volcanic rocks on the western side of the South Kenya Rift Valley are presented. Nine stratigraphic groups ranging in age from Miocene to Pleistocene were sampled. The rocks consist of basalts, trachytes, nephelinites, melanephelinites, olivine melanephelinites and ignimbrites. Paleomagnetic poles obtained for different age ranges are as follows: Period I (0.64–0.72 Ma), 116°E, 85°N (A₉₅ = 6°); Period II (1.6–6.9 Ma), 297°E, 84°N (A₉₅ = 4°); Period III (12.0–15.0 Ma), 34°E, 80°N (A₉₅ = 9°). The results for Period II show large secular variations which are in disagreement with the model predictions for near-equatorial sites.  相似文献   

Monsoon activity and coupling between low-latitude and high-latitude stratospheric activities     

K. S. Raja Rao  S. T. Awade  M. V. Harindranathan Nair 《Pure and Applied Geophysics》1983,121(5-6):1035-1048

From a Fourier analysis of the monthly mean values of the northern hemispheric geopotential heights at 30 and 50 mb levels, for the period 1972–1979, the transports of momentum and of sensible heat, and the energy conversion terms,C(K _E ,K _Z ) andC(A _Z ,A _E ), have been computed along 30°N and 60°N latitutudes. The variation in these dynamical parameters at 60°N, in relation to monsoon activity in low latitudes and the easterly and westerly phases of the QBO over Gan Island, suggest that a coupling may exist between the high-latitude stratospheric changes and low-latitude monsoon activity and that the low-latitude stratospheric activity modulates high-latitude circulation, confirming the results obtained byHolton andTan (1980) and byLabitzke (1983). The study of the low-latitude stratospheric changes in relation to the high-latitude warmings also indicates a linkage between the low- and high-latitude features  相似文献   

Influence of geological factors on abrasion and soundness characteristics of aggregates     

Asadullah Kazi  Zuhdi Raja Al-Mansour 《Engineering Geology》1980,15(3-4):195-203

A study has been made of the abrasion and soundness characteristics of crushed-rock aggregates obtained from a wide variety of igneous rocks of volcanic and plutonic origins, that range from acidic to basic in composition. The grain size and the volume of pore spaces were found to be the significant geological factors controlling the evaluation of these two parameters. Fine-grained rocks when compared with coarse-grained rocks having the same porosity were found to be more sound and more resistant to wear.  相似文献